Add select mapping to Observable

Author: flowtoolz

Code/Mapping+StandardMappings.swift

@@ -1,12 +1,12 @@
-extension Mapping where MappedUpdate: Equatable
+public extension Mapping where MappedUpdate: Equatable
 {
     public func select(_ default: MappedUpdate) -> Mapping<O, Void>
     {
         return map(prefilter: { $0 == `default` }) { _ in }
     }
 }
 
-extension Mapping
+public extension Mapping
 {
     public func new<Value>() -> Mapping<O, Value>
         where MappedUpdate == Update<Value>

Code/Observable+StandardMappings.swift

@@ -1,3 +1,11 @@
+public extension Observable where UpdateType: Equatable
+{
+    public func select(_ default: UpdateType) -> Mapping<Self, Void>
+    {
+        return map(prefilter: { $0 == `default` }) { _ in }
+    }
+}
+
 public extension Observable
 {
     public func new<MappedUpdate>() -> Mapping<Self, MappedUpdate>

Tests/SwiftObserverTests/SwiftObserverTests.swift

@@ -182,6 +182,25 @@ class SwiftObserverTests: XCTestCase
         XCTAssert(!didFire)
     }
 
+    func testMappingSelectOnCustomObservable()
+    {
+        let mappedModel = model.select(.didUpdate)
+        
+        var didFire = false
+        
+        controller.observe(mappedModel)
+        {
+            didFire = true
+        }
+        
+        model.send(.didUpdate)
+        XCTAssert(didFire)
+        
+        didFire = false
+        model.send(.didReset)
+        XCTAssert(!didFire)
+    }
+    
     func testMultiplication()
     {
         XCTAssertEqual(Var(2) * Var(7), 14)
@@ -574,12 +593,17 @@ class SwiftObserverTests: XCTestCase
 
     func testObservableMapping()
     {
-        controller.observe(model.map { $0.rawValue })
+        var didFire = false
+        
+        controller.observe(model).map({ $0.rawValue })
         {
             XCTAssertEqual($0, "didUpdate")
+            didFire = true
         }
 
         model.send(.didUpdate)
+        
+        XCTAssert(didFire)
     }